A small group of rare and unusual meteorites, consisting of three main subgroups: the shergottites, nakhlites, and chassignites (hence SNC). The SNC meteorites are igneous rocks that solidified from a cooling magma near the surface of their parent body, probably Mars. All are relatively young, less than 1.3 billion years old. The proportions and isotopic abundances of noble gases trapped in SNC meteorites resemble the composition of the atmosphere of Mars as analysed by several Martian landers. SNC meteorites were probably ejected from Mars by impacts, and entered orbits around the Sun before falling to Earth.